Catalytic Activation of a Carbon-Chloride Bond by Dicationic Tellurium-Based Chalcogen Bond Donors

Article abstract of DOI:10.1055/a-1372-6309

Noncovalent interactions such as halogen bonding (XB) and chalcogen bonding (ChB) have gained increased interest over the last decade. Whereas XB-based organocatalysis has been studied in some detail by now, intermolecular ChB catalysis only emerged quite

Full text of DOI:10.1055/a-1372-6309

SYNTHESIS
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Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart
2021, 53, A–H
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T. Steinke et al.
Feature
Synthesis
Catalytic Activation of a Carbon–Chloride Bond by Dicationic
Tellurium-Based Chalcogen Bond Donors
Tim Steinke
Patrick Wonner
Elric Engelage
Stefan M. Huber*
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Fakultät für Chemie und Biochemie, Ruhr-Universität Bochum,
Universitätsstraße 150, 44801 Bochum, Germany
stefan.m.huber@rub.de
SFeaMtekfauaiClntosäMtrterf.efüaHsrnpuC.ombhne.edrhmiunbigeeAru@untrdhuoBbri.odcehemie, Ruhr-Universität Bochum, Universitätsstraße 150, 44801 Bochum, Germany
Received: 01.12.2020
Accepted after revision: 25.01.2021
Published online: 25.01.2021
ing strength can be fine-tuned by variation of the chalcogen
(S < Se < Te). Also, the superior directionality of approxi-
mately 170° could be beneficial for high substrate selectivi-
ty.5,7,8
DOI: 10.1055/a-1372-6309; Art ID: ss-2020-z0617-fa
Abstract Noncovalent interactions such as halogen bonding (XB) and
chalcogen bonding (ChB) have gained increased interest over the last
decade. Whereas XB-based organocatalysis has been studied in some
detail by now, intermolecular ChB catalysis only emerged quite recent-
ly. Herein, bidentate cationic tellurium-based chalcogen bond donors
are employed in the catalytic chloride abstraction of 1-chloroisochro-
man. While selenium-based ChB catalysts showed only minor activity in
this given benchmark reaction, tellurium-based variants exhibited
strong activity, with rate accelerations of up to 40 relative to non-chalo-
genated reference compounds. In general, the activity of the catalysts
improved with weaker coordinating counterions, but tetrafluoroborate
took part in a fluoride transfer side reaction. Catalyst stability was con-
firmed via a fluoro-tagged variant.
Several fascinating applications of chalcogen bonding in
the solid state9 are already known, along with its use in an
intramolecular fashion in organic synthesis.10 In the last
years, Taylor,11 Beer,4b,12 and Matile13 applied ChB in anion
recognition as well as transport and thus described first in-
termolecular applications in solution.14 In 2017, Matile re-
ported the catalytic reduction of quinolines by sulfur-based
ChB donors, which constitutes the first use of such species
as noncovalent organocatalysts.15 Subsequently, our group
employed selenium-based ChB donors for the activation of
carbon–halide bonds and in the above-mentioned quino-
line reduction as benchmark.16 Due to the weaker interac-
tion of neutral substrates with ChB bond donors, the activa-
tion of such compounds is more challenging. Shortly after
the first report of a carbonyl activation via Se-based ChB
donors by Wang,17 our group introduced the first cationic
tellurium-based ChB organocatalysts and employed them in
the activation of trans--nitrostyrene as well as trans-cro-
tonophenone in (nitro)-Michael addition reactions.18 These
bidentate ChB donors are also expected to be the most ac-
tive catalysts in halide abstraction reactions, but the use of
Te-derived species in such reactions has so far been limited
to the application of neutral polyfluorinated variants,19
which are typically much weaker Lewis acids compared to
(di)cationic ChB donors.
Key words chalcogen bonding, organocatalysis, halide abstraction,
Lewis acids, intermolecular interactions, noncovalent interactions
Besides hydrogen bonding, the dominating noncovalent
interaction in organocatalysis,1 other interactions, such as
anion-,2 halogen bonding (XB),3 and chalcogen bonding
(ChB),4 have recently attracted more attention in this field
of research. In contrast to halogen bonding, which has been
employed in organocatalysis for about a decade now,3a chal-
cogen bonding has been far less studied in this regard.
This interaction between Lewis acidic chalcogen atoms
in organic or inorganic molecules and Lewis bases can be
rationalized by attractive contributions both from orbital
interactions5 (i.e., n → * charge transfer)6 and electrostat-
ics. The latter is based on a region of positive electrostatic
potential on the elongation of the R–Ch bond, the so called
-hole.7 Chalcogen bonds have the advantage that the bind-
Herein, we now present the first carbon–halogen bond
activation by cationic tellurium-based catalysts. Since this
study is primarily meant to provide further data on the per-
formance and structure-activity relationship of ChB donors
© 2021. Thieme. All rights reserved. Synthesis 2021, 53, A–H
Georg Thieme Verlag KG, Rüdigerstraße 14, 70469 Stuttgart, Germany

B
T. Steinke et al.
Feature
Synthesis
(also in comparison to HB and XB donors), we chose to use
an often-employed benchmark reaction,19,20 the nucleophilic
substitution of 1-chloroisochroman (1) with a ketene silyl
acetal 2 (Scheme 1). This reaction is ideal for this purpose
since it features no background reaction and because it is
immune to hidden acid catalysis.20b,21
10 mol% catalyst
THF (90.0 mM)
CO2CH3
O
Cl
OTBS
OCH3
+
O
–78 °C, 12 h
– TBSCl
1
2
3
Scheme 1 Benchmark reaction of the chloride abstraction involving 1-
chloroisochroman (1) with catalytic amounts of chalcogen bond donor
Biographical Sketches
Tim Steinke, born 1993 in
Eschwege, studied chemistry at
the Ruhr-Universität Bochum
(RUB) and received his Master’s
degree in 2019. Currently, he is
a Ph.D. student in the group of
Prof. Stefan M. Huber at the
RUB. His research focuses on
the synthesis and application of
multidentate chalcogen bond
donors in organic synthesis.
Patrick Wonner, born in July
1991, studied chemistry at the
Ruhr-Universität Bochum. He
finished his bachelor’s degree in
the year 2014 and received his
Master’s degree in 2016. The
master thesis was prepared in
the group of S. M. Huber in the
field of halogen bonding. Subse-
quently, he started his Ph.D. in
the same group about the ap-
plication of halogen and chalco-
gen bonding in organocatalysis
and finished his research in April
2020 to receive his Ph.D.
Elric Engelage was born in
Germany in 1990. He obtained
his B.Sc. in Biochemistry from
the Ruhr-Universität Bochum.
For his master and doctoral
studies in Chemistry he joined
the workgroup of Prof. S. M. Hu-
ber, focusing on halogen bond-
ing in solution, and serving as
the group’s crystallographer.
After obtaining his doctoral de-
gree in 2019 he transferred to
the group of Prof. W. Sander.
Stefan M. Huber, born in
1977, studied chemistry at the
Friedrich-Alexander-University
Erlangen-Nuremberg and ob-
tained his Ph.D. degree in 2007
with Prof. Robert Weiss. After
postdoctoral stays at the Uni-
versity of Minnesota and the
University of Geneva, he started
his independent career at TU
Munich in 2009. Since 2014, he
is professor of organic chemis-
try at Ruhr-University Bochum.
© 2021. Thieme. All rights reserved. Synthesis 2021, 53, A–H

C
T. Steinke et al.
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Synthesis
Previously, we had used the same reaction to introduce
1,3-bis(selenobenzimidazolium)benzene derivatives as
ChB-based organocatalysts,16b these ChB donors were how-
ever susceptible to decomposition by dealkylation on the
chalcogen center.16a Even though this is not feasible for the
catalysts used in this study (like compound 14, see Figure 2)
due to the presence of a phenyl substituent, we neverthe-
less wanted to be able to check catalyst stability during the
reaction. To this end, we synthesized fluorine-tagged vari-
ants like 8 and 9 (Scheme 2) which can easily be monitored
by 19F NMR spectroscopy. The synthetic route to these cata-
lysts followed already known procedures (Scheme 2).18 1,3-
Diethynyl-5-fluorobenzene is not commercially available
and was therefore synthesized from the available 1,3-di-
bromo-3-fluorobenene by Sonogashira coupling with
(trimethylsilyl)acetylene and subsequent deprotection.22
The following steps involve a 1,3-dipolar cycloaddition re-
action23 of the alkyne moieties with azides to build up the
triazole groups, and the formation of the chalcogen ether in
basic media. The cationic catalysts were then obtained after
methylation with Me3OBF4. Triflate salt 9 was obtained via
anion exchange resin from 8, as direct methylation with
methyl trifluoromethanesulfonate led to impure com-
pounds. Similarly, the non-fluorine-tagged catalysts 14OTf
and 15OTf (see Figure 2) were also synthesized by ion ex-
change. To confirm the purity of the compounds and espe-
cially to rule out the presence of trifluoromethanesulfonic
acid (HOTf), the recently proposed purity check by Franz et
al. for halogen bond donors was employed.24 Indeed, addi-
tion of triethylphosphine oxide to 14OTf showed a clear and
sharp peak in the corresponding 31P NMR spectrum. Resid-
ual HOTf would lead to a broad peak, which was confirmed
by the addition of this acid, thus further validating the
method.
F
F
i)
ii)
Br
Br
4
5
iii)
F
F
N
N
iv)
N
N
N
N
N
N
N
N
N
N
Te
Ph
Te
Ph
C8H17
C8H17
C8H17
C8H17
7
6
v)
F
F
N
N
N
N
N
N
vi)
N
N
N
N
N
N
Te
Ph
Te
Ph
Te
Ph
Te
Ph
C8H17
C8H17
C8H17
C8H17
2 BF4
2 OTf
8
9
Scheme 2 Synthesis of fluorine-tagged chalcogen bonding organocat-
alysts. Reagents and conditions: (i) Me3SiC≡CH, Pd(PPh3)4, CuI, THF,
Et3N, 70 °C, 2 d; (ii) CsF, EtOH, r.t., 30 min; (iii) n-C8H17N3, CuI, TBTA,
THF, r.t., light exclusion, 3 d; (iv) i-Pr2NH, n-BuLi, (PhTe)2, THF, –78 °C →
r.t., 18 h; (v) Me3OBF4, CH2Cl2, r.t., 18 h; (vi) Amberlyst® A26 (OH),
HOTf, MeOH.
in the reaction and again did not show any activity (Table 1,
entry 12). The corresponding halogen-bond donor 13OTf, on
the other hand, generated comparable yields to 14OTf (Table
1, entry 13).
First catalysis experiments were carried out with 14BF4
.
However, less than 5% yield of product 3 was obtained with
10 mol% of this catalyst after 12 h at –78 °C (Table 2, entry
2). Therefore, the corresponding triflate salt 14OTf was then
tested, and with this catalyst, product 3 was obtained in
82% yield under the same conditions (Table 2, entry 3). To
rule out other modes of activation except chalcogen bond-
ing, several reference compounds were also studied in par-
allel, which included elemental tellurium and selenium, di-
chalcogenides 10, neutral/non-alkylated ChB donors 11,
and non-chalcogenated variant 12OTf (Figure 1). All of these
compounds showed only low or no activity (Table 1, entries
2–7), with hydrogen-bond donor 12OTf providing a mere
yield of 9% (Table 1, entry 8). To exclude any innate activity
of the counterions, their ammonium salts were also tested,
but no formation of 3 was observed in any of these experi-
ments (Table 1, entries 9–11). As compounds 14OTf and
15OTf are prepared by anion exchange chromatography, the
Amberlyst resin used for this exchange was also employed
N
N
Ch
N
N
Ch
N
N
Ch
Ph
Ch
Ph
C8H17
C8H17
10Ch
11Ch
N
N
N
N
N
N
N
N
N
N
N
N
H
H
I
I
C8H17
C8H17
C8H17
C8H17
2 OTf
2 OTf
13OTf
12OTf
Figure 1 Selected reference compounds tested in the benchmark re-
action to rule out activation based on other interactions than chalcogen
bonding; Ch = Se, Te
© 2021. Thieme. All rights reserved. Synthesis 2021, 53, A–H

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T. Steinke et al.
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Table 1 NMR Yields of 3 in the Presence of the Activation Compounds
after 12 h at –78 °C
With these findings in hand, the influence of structural
variations was investigated using the catalysts shown in
Figure 2.
Entry
Catalyst
mol%a
Yield (%) of 3b
1
–
–
<5
<5
<5
<5
<5
<5
<5
9
N
N
N
N
2
Te
20
20
10
10
10
10
10
20
20
20
20
10
N
N
N
N
N
N
N
N
3
Se
Te
Ph
Te
Ph
Se
Ph
Se
Ph
C8H17
C8H17
C8H17
C8H17
4
10Te
5
10Se
2 Z
2 Z
14Z
15Z
6
11Te
7
11Se
8
12OTf
Me4NBF4
Et4NOTf
Me4NBArF
Amberlystc
13OTf
N
N
N
N
9
<5
<5
8
N
N
Te
Ph
H
10
11
12
13
C8H17
C8H17
2 OTf
16OTf
<5
86
Figure 2 Tested chalcogen bond donors; Z = BF4, OTf, BArF
a Equivalents of catalyst with respect to 1.
4
b ±5% measurement error assumed.
c Results for the used and unused Amberlyst are combined in this entry.
Comparable activity as for 14OTf was observed for 14BArF4
with 83% yield (Table 2, entry 4). Interestingly, a higher
amount of diisochroman ether was formed when using
Similar performance was also observed for the fluorine-
tagged variant 9OTf compared to its parent compound 14OTf
(Table 2, entries 1 and 3). The stability of the former was
then investigated by 19F NMR spectroscopy of the reaction
mixture after the reaction time of 12 h. The spectrum
shows only the corresponding Carom–F signal of the ChB do-
nor and the signal for triflate. Addition of the pure catalysts
to the mixture and repeating the 19F experiment showed
again only these two signals. Thus, decomposition of the
catalyst can be ruled out and the combination of all these
reference experiments clearly points to chalcogen bonding
as the mode of action.
BArF -containing catalysts, most likely due to increased hy-
4
groscopic properties. Since the similar yields induced by
14BArF4 and 14OTf may at least be partially due to the fact
that the reaction has already reached a plateau-like phase,
additional kinetic measurements were performed to inves-
tigate the influence of the counterion more closely (see Fig-
ure 3). Here, a superior performance of 14BArF4 was clearly
observable: after 1 h, 31% of product was generated com-
pared to 15% for 14OTf. This stronger acceleration, which is
also reflected in the relative rate constants referenced to HB
donor 12OTf (krel = 41 vs. krel = 20), is likely based on the
weaker coordination of the BArF counterion to the Lewis
4
Table 2 NMR Yields of 3 in the Presence of the Activation Compounds
after 12 h at –78 °C
acidic chalcogen center. In addition, a kinetic profile of the
reaction involving XB reference compound 13OTf was also
taken and it demonstrated the even superior performance
Entry
Catalyst
mol%a
Yield (%) of 3b
of structurally comparable XB donors in this reaction (krel
=
9OTf
60).
1
2
3
4
5
6
7
8
10
10
10
10
10
10
10
10
77
<5
82
83
<5
6
At first glance, the low performance of 14BF4 may seem
puzzling in light of the yields generated by 14OTf, which
should feature a more coordinating counterion. When the
reaction was monitored by 19F NMR spectroscopy, however,
the reason for this inactivity became clear, as a new septet
at –171.3 ppm was observed, which is characteristic of tert-
butyldimethylsilyl fluoride.25 Thus, apparently fluoride
14BF4
14OTf
14BArF4
15BF4
15OTf
15BArF4
16OTf
15
41
transfer from BF4 to the released TBS+ moiety takes place,
resulting in formation of the chloride salt of the catalyst,
which is not catalytically active. This finding was corro-
borated by measurements involving catalyst 8, which
–
a Equivalents of catalyst with respect to 1.
b ±5% measurement error assumed.
–
showed that a complete conversion of BF4 into BF3 takes
place under reaction conditions, again yielding no product.
© 2021. Thieme. All rights reserved. Synthesis 2021, 53, A–H

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T. Steinke et al.
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performances mentioned above, the resulting adduct (Fig-
ure 4) features two equally strong ChBs (with bond distanc-
es of 2.88 Å and angles of 164°).
Figure 3 Kinetic plot of the chloride abstraction of 1 as yield versus
time profile with 1H NMR determined yields
Next, we tested the selenium-based analogues of our
catalysts (Table 2, entries 5–7). It should be noted that the
duration of the benchmark reaction was reduced by a factor
of ten in this study compared to the experiments employ-
ing our previously reported bis(selenobenzimidazolium)-
based ChB donors.16b The latter are also more preorganized
than the core structures of the catalysts used herein. In ac-
cord with the observation of 14BF4 not catalyzing the reac-
tion, 15BF4 also showed no activity (Table 2, entry 5). Triflate
salt 15OTf, on the other hand, provided a slight yield of 6%
Figure 4 Calculated complex of 14 and chloride (Graphics by CYL-
view30
)
In conclusion, the catalytic activation of a carbon–halo-
gen bond by bidentate and cationic tellurium-based chalco-
gen bond donors was presented. In line with expectations,
selenium-based analogues were markedly less active while
non-coordinating counterions increased the performance
of the catalyst, with the exception of tetrafluoroborate,
which led to fluoride transfer. Via several comparison ex-
periments, including a stability check of a fluorine-tagged
catalyst variant, the crucial role of chalcogen bonding was
confirmed.
(Table 2, entry 6). In this case, the less coordinating BArF
4
counterion leads to some improvement, as 15% yield was
found for 15BArF4 (Table 2, entry 7). Overall, still, all tested
selenium-based ChB donors with the 1,3-bis(triazoli-
um)benzene scaffold seem much less suitable for halide ab-
straction than their tellurium equivalents. The same low ac-
tivity was already reported for structurally closely related
1,3-bis(imidazolium)benzene-based catalysts.16b
Furthermore, to determine the cooperative effect of the
bidentate catalysts, monodentate analogue 16OTf, which
features only one Lewis acidic tellurium center, was also ap-
plied in 10 mol% loading (Table 2, entry 8). Since hydrogen
bond donor 12OTf showed little activity (Table 1, entry 8), it
is reasonable to assume that the contribution of a potential
additional hydrogen bond can be neglected. With com-
pound 16OTf, a yield of 41% was observed, which is approxi-
mately half that obtained with 14OTf, and thus based on this
orientating comparison, the cooperative effect does not
seem very pronounced.
To obtain a better understanding of the possible geome-
try of a chloride complex of catalyst 14, DFT calculations
were carried out in parallel (using the M06-2X functional26
with D3 dispersion corrections27 and the triple-zeta TZVP
basis set28 as well as the intrinsic solvation model SMD1829
with parameters for THF). In some contrast to the catalyst
All chemicals were purchased from commercially available sources
and used without further purification, if not stated otherwise. All re-
actions were carried out under argon atmosphere using standard
Schlenk techniques, oven-dried or flame-dried glassware, and dry
solvents. Dry CH2Cl2, Et2O, and THF were received from a MBRAUN
MB SPS-800. The solvents were distilled and dried over 4-Å molecular
sieves and finally dried on an alox column. Other dry solvents were
dried with flame-dried 4-Å molecular sieves. Residual water was de-
termined by a Karl Fischer Titroline® 7500KF trace. Merck TLC alumi-
num sheets (silica gel 60, F254) were used for thin layer chromatogra-
phy. Substances were detected by fluorescence under UV light (wave-
length  = 254 nm). Column chromatography was performed with
silica gel (0.04–0.063 mm, Merck Si60) and distilled solvents. 1H NMR
spectra as well as 13C were recorded with a Bruker AVIII 300 and a
Bruker AVIII 400 spectrometer at r.t. 19F NMR and 31P NMR were
recorded with a Bruker DPX-250 spectrometer at r.t. and were
measured proton decoupled if not further noted. ESI-MS spectra were
recorded with a Bruker Esquire 6000 with compounds dissolved in
MeCN or MeOH. IR spectra were recorded with a Shimadzu IR
© 2021. Thieme. All rights reserved. Synthesis 2021, 53, A–H

F
T. Steinke et al.
Feature
Synthesis
Affinity-IS spectrophotometer. For stock solutions a Mettler Toledo
XSR 105 Dual Range balance was used to weight starting material.
TBTA = tris[(1-benzyl-1H-1,2,3-triazol-4-yl)methyl]amine.
1-Fluoro-3,5-bis[1-octyl-5-(phenyltellanyl)-1H-1,2,3-triazol-4-
yl]benzene (7)
An already published procedure was adapted for the synthesis of
compound 7.18a In a flame-dried Schlenk flask, i-Pr2NH (1.02 mL,
0.735 g, 7.26 mmol, 2.20 equiv) was mixed with dry THF (33.0 mL,
0.10 M) and the mixture cooled to 0 °C. Afterwards, 2.5 M n-BuLi
(3.17 mL, 7.92 mmol, 2.40 equiv) was added dropwise over a period
of 15 min and the solution was stirred for 30 min at 0 °C. The solution
was then cooled to –78 °C, stirred for 15 min and 6 (1.50 g, 3.30
mmol, 1.00 equiv) in THF (33.0 mL, 0.10 M) was added dropwise. The
mixture was stirred for 3 h at –78 °C and subsequently diphenyl ditel-
luride (3.38 g, 8.25 mmol, 2.50 equiv) in dry THF (82.5 mL, 0.10 M)
was added in one portion. The mixture was stirred and warmed to r.t.
for 18 h. The solvent was removed under reduced pressure and the
residue purified by column chromatography (pentane/EtOAc 3:1; Rf =
0.79) to give 7 as a yellow sticky oil; yield: 1.37 g (1.59 mmol, 48%).
Compounds 5,22 11Te 18a
15BF4 18a 15BArF418b were synthesized according to literature proce-
dures.
,
11Se,18a 12OTf 31 13OTf 31 14BF4 18a 14BArF4 18a
, , , ,
,
General Anion Exchange Procedure
The general procedure is modified from an already published proce-
dure.32 Amberlyst® A26 (OH) (1 g per 100 mg of the respective tetra-
fluoroborate salt) was suspended in MeOH (10 mL per g resin), care-
fully stirred and cooled to 0 °C. After 15 min, HOTf (20.0 mmol per g
resin) was added dropwise over a period of 10 min. The mixture was
carefully stirred for 30 min at 0 °C and then poured into a thin glass
column and rinsed with MeOH until a neutral pH was obtained. Sub-
sequently, the respective tetrafluoroborate salt dissolved in MeOH
(0.05 M) was poured onto the column and rinsed slowly through the
column. The collected solution was rinsed twice more through the
column and finally the column was rinsed with MeOH (50 mL). The
solvent was removed under reduced pressure and the residue dried
under high vacuum to obtain the triflate salt.
IR (ATR): 3067 (w), 2922 (s), 2853 (s), 1734 (w), 1616 (w), 1591 (m),
1574 (m), 1474 (m), 1435 (m), 1319 (m), 1238 (m), 1121 (w), 1017
(m), 997 (m), 905 (m), 868 (m), 802 (m), 727 (vs), 689 (vs), 652 (w),
530 (w), 451 cm–1 (m).
4
1H NMR (300 MHz, CDCl3):  = 8.45 (t, J = 1.5 Hz, 1 H, C-CH-C), 7.73
3
4
(dd, J = 9.7 Hz, J = 1.5 Hz, 2 H, CH-CF-CH), 7.42–7.34 [m, 4 H, Te-C-
(CH-CH)2CH], 7.26–7.09 [m, 6 H, Te-C-(CH-CH)2CH], 4.51 (d, 3J = 7.5
Hz, 4 H, N-CH2-CH2), 1.79 (p, J = 7.5 Hz, 4 H, N-CH2-CH2), 1.35–1.15
1-Fluoro-3,5-bis(1-octyl-1H-1,2,3-triazol-4-yl)benzene (6)
3
An already published procedure was adapted for the synthesis of
compound 6.31 In dry and degassed THF (62.5 mL, 20.0 mM), CuI
(0.238 mg, 1.25 mmol, 0.10 equiv), and TBTA (0.663 g, 1.25 mmol,
0.10 equiv) were dissolved and stirred for 2 h at r.t. This mixture was
added to a solution of 1,3-diethynyl-5-fluorobenzene (1.80 g, 12.5
mmol, 1.00 equiv) in dry and degassed THF (16.0 mL, 0.80 M). A solu-
tion of octyl azide (3.88 g, 25.0 mmol, 2.00 equiv) in dry and degassed
THF (16 mL, 1.59 M) was slowly added over a period of 10 min. The
resulting mixture was stirred at r.t. for 3 d under light exclusion. The
solvent was removed under reduced pressure and the residual was
taken up in EtOAc. The mixture was extracted with a basic aq EDTA
solution (3 × 75 mL). The organic layer was extracted with water (2 ×
100 mL) and brine (1 × 100 mL) and dried (Na2SO4). The solvent was
removed under reduced pressure and the crude solid was purified by
column chromatography (pentane/EtOAc 2:1; Rf = 0.55) to give the
product as a pale yellow solid; yield: 4.97 g (10.9 mmol, 87%).
(m, 20 H, Haliph), 0.93–0.82 (m, 3 H, CH2-CH3).
1
13C NMR (75 MHz, CDCl3):  = 162.73 (d, JC-F = 244.8 Hz, Carom-F),
4
153.1 (d, JC-F = 2.8 Hz, CH-C-CHarom-C-CH), 136.2 (Carom), 133.7 (d,
3JC-F = 9.1 Hz, C-Ctriazole), 130.2 (Carom), 128.6 (Carom), 123.9 (Carom), 115.2
(d, 2JC-F = 23.2 Hz, CaromF-CaromH), 114.2 (Carom), 102.6 (Carom), 51.6 (Caliph),
31.9 (Caliph), 30.8 (Caliph), 29.2 (Caliph), 29.1 (Caliph), 26.6 (Caliph), 22.8
(Caliph), 14.2 (Caliph).
19F NMR (235 MHz, CDCl3):  = –112.75 (s, 1 F, Carom-F).
MS (ESI): m/z (+) calcd for [M + Na]+: 885.02; found: 885.46.
4,4′-(1-Fluoro-3,5-phenylene)bis[3-methyl-1-octyl-5-(phenyl-
tellanyl)-1H-1,2,3-triazol-3-ium] Tetrafluoroborate (8)
An already published procedure was adapted for the synthesis of
compound 8.18a Under inert gas atmosphere, compound 7 (0.344 g,
0.399 mmol, 1.00 equiv) was dissolved in dry CH2Cl2 (8.00 mL, 0.05
M). Subsequently, trimethyloxonium tetrafluoroborate (0.148 g, 0.997
mmol, 2.50 equiv) was added to the yellow solution and the mixture
stirred at r.t. for 18 h. The solvent was removed under reduced pres-
sure and the residue washed with Et2O (3 × 30 mL) and pentane (3 ×
30 mL) and dried under high vacuum to obtain 13 as a pale yellow
sticky solid; yield: 0.373 g (0.350 mmol, 88%).
IR (ATR): 3146 (w), 2953 (m), 2918 (vs), 2853 (s), 1622 (w), 1604 (m),
1562 (w), 1470 (vs), 1427 (m), 1360 (m), 1346 (w), 1305 (w), 1227
(s), 1150 (s), 1082 (w), 1051 (m), 895 (vs), 858 (vs), 808 (vs), 791 (s),
754 (w), 721 (s), 677 (s), 654 (s), 536 (w), 496 (w), 448 (w), 410 cm–1
(w).
1H NMR (300 MHz, CDCl3):  = 8.08 (t, 4JH-H = 1.4 Hz, 1 H, C-CH-C), 7.84
(s, 2 H, Htriazole), 7.53 (dd, 3JF-H = 9.5 Hz, 4JH-H = 1.4 Hz, 2 H, CH-CF-CH),
4.42 (t, 3JH-H = 7.2 Hz, 4 H, Ctriazole-CH2-CH2), 1.95 (q, 3JH-H = 7.3 Hz, 4 H,
Ctriazole-CH2-CH2), 1.29 (m, 20 H, Haliph), 0.86 (m, 6 H, CH3).
IR (ATR): 3075 (w), 2926 (m), 2855 (m), 1603 (w), 1574 (w), 1547 (w),
1460 (w), 1435 (m), 1328 (m), 1287 (w), 1182 (w), 1047 (vs), 1030
(vs), 995 (vs), 932 (s), 887 (m), 849 (m), 732 (s), 689 (s), 654 (m), 600
(w), 519 (m), 453 cm–1 (m).
1H NMR (300.1 MHz, CDCl3):  = 7.87 (t, 4J = 1.2 Hz, 2 H, C-CH-C), 7.56
(dd, 3J = 8.5 Hz, 3J = 1.3 Hz, 2 H, CH-CF-CH), 7.47 [dd, 3J = 8.0 Hz, 4J = 1.5
Hz, 4 H, Te-C-(CH-CH)2CH], 7.31–7.16 [m, 6 H, Te-C-(CH-CH)2CH],
4.59 (d, 3J = 7.5 Hz, 4 H, N-CH2-CH2), 4.19 (s, 6 H, N-CH3), 1.87 (d, 3J =
7.7 Hz, 4 H, N-CH2-CH2), 1.40–1.15 (m, 20 H, Haliph), 0.94–0.83 (m, 6 H,
CH2-CH3).
13C NMR (75 MHz, CDCl3):  = 163.6 (d, 1JC-F = 245.3 Hz, Carom-F), 146.5
(d, 4JC-F = 2.9 Hz, CH-C-CHarom-C-CH), 133.4 (d, 3JC-F = 9.1 Hz, C-Ctriazole),
2
120.2 (Ctriazole), 118.5 (Ctriazole), 112.1 (d, JC-F = 23.3 Hz, CaromF-CaromH),
50.7 (Caliph), 31.8 (Caliph), 30.4 (Caliph), 29.2 (Caliph), 29.1 (Caliph), 26.6
(Caliph), 22.7 (Caliph), 14.2 (Caliph).
19F NMR (235 MHz, CDCl3):  = –112.3 (s, 1 F, Carom-F).
MS (ESI): m/z (+) calcd for [M + Na]+: 477.31; found: 477.23; m/z (+)
calcd for [M + K]+: 493.42; found: 493.06.
1
13C NMR (75.5 MHz, CDCl3):  = 162.29 (d, JC-F = 251.8 Hz, Carom-F),
147.7 (d, 4JC-F = 2.4 Hz, CH-C-CHarom-C-CH), 137.8 (Carom), 130.8 (Carom),
129.7 (Carom), 129.0 (Carom), 127.0 (d, 3JC-F = 9.4 Hz, C-Ctriazole), 121.7 (d,
© 2021. Thieme. All rights reserved. Synthesis 2021, 53, A–H

G
T. Steinke et al.
Feature
Synthesis
2JC-F = 24.2 Hz, CaromF-CaromH), 114.2 (Carom), 112.1 (Carom), 55.6 (Caliph),
39.1 (Caliph), 31.8 (Caliph), 29.3 (Caliph), 29.0 (Caliph), 28.9 (Caliph), 26.36
(Caliph), 22.7 (Caliph), 14.2 (Caliph).
19F NMR (235.6 MHz, CDCl3):  = –107.1 (s, 1 F, Carom-F), –152.6 (d, 8 F,
BF4).
5-(Phenyltellanyl)-4,4′-(1,3-phenylene)bis(3-methyl-1-octyl-1H-
1,2,3-triazol-3-ium) Triflate (16OTf
)
Compound 16OTf was synthesized according to the general anion ex-
change procedure using Amberlyst® A26 (OH) (2.50 g), MeOH (25
mL), and tetrafluoroborate salt (0.250 g, 0.296 mmol) dissolved in
MeOH (5.92 mL) to give 16OTf as a pale yellow sticky solid; yield: 0.205
g (0.213 mmol, 72%).
MS (ESI): m/z (+) calcd for [M – BF4]+: 978.91; found: 979.33; m/z (–)
calcd for [BF4]–: 86.80; found: 86.79.
IR (ATR): 3078 (w), 2955 (w), 2926 (m), 2857 (w), 1572 (w), 1466 (w),
1437 (w), 1252 (vs), 1223 (vs), 1152 (vs), 1028 (vs), 997 (w), 916 (w),
837 (w), 808 (w), 754 (w), 737 (m), 691 (m), 635 (vs), 573 (m), 517
(vs), 455 cm–1 (m).
4,4′-(1-Fluoro-3,5-phenylene)bis[3-methyl-1-octyl-5-(phenyl-
tellanyl)-1H-1,2,3-triazol-3-ium] Triflate (8)
Compound 9 was synthesized according to the general anion ex-
change procedure using Amberlyst® A26 (OH) (3.40 g), MeOH (34
mL), and compound 8 (0.336 g, 0.316 mmol) dissolved in MeOH (6.32
mL) to give 9 as a pale yellow sticky solid; yield: 0.333 g (0.280 mmol,
89%).
1H NMR (300 MHz, CDCl3):  = 9.00 (s, 1 H, Htriazole), 8.16 (d, 4J = 1.4 Hz,
1 H, C-CH-C), 8.03 (dt, 3J = 7.8 Hz, 4J = 1.4 Hz, 1 H, C-CH-CH-CH-C),
3
4
3
7.80 (dt, J = 7.9 Hz, J = 1.3 Hz, 1 H, C-CH-CH-CH-C), 7.68 (t, J = 7.8
Hz, 1 H, C-CH-CH-CH-C), 7.47 [dt, 3J = 6.9 Hz, 4J = 1.4 Hz, 2 H, Te-C-
(CH-CH)2CH], 7.31–7.13 [m, 4 H, Te-C-(CH-CH)2CH], 4.65 (t, 3J = 7.7
Hz, 2 H, Ctriaz.H-CH2-CH2), 4.60 (t, 3J = 7.5 Hz, 2 H, Ctriaz.TePh-CH2-CH2),
4.35 (s, 3 H, Ntriaz.H-CH3), 4.19 (s, 3 H, Ntriaz.TePh-CH3), 2.08 (q, 3J = 7.5 Hz,
2 H, Ctriaz.H-CH2-CH2), 1.91 (p, 3J = 7.7 Hz, 2 H, Ctriaz.TePh-CH2-CH2), 1.49–
1.18 (m, 20 H, Haliph), 0.94–0.82 (m, 6 H, CH2-CH3).
IR (ATR): 3059 (w), 2926 (m), 2857 (w), 1603 (w), 1574 (w), 1547 (w),
1460 (w), 1435 (w), 1246 (vs), 1223 (vs), 1152 (vs), 1026 (vs), 997
(m), 932 (m), 885 (w), 851 (w), 733 (s), 689 (s), 656 (w), 635 (vs), 573
(m), 515 (vs), 453 cm–1 (m).
4
1H NMR (300 MHz, CDCl3):  = 8.07 (t, J = 1.3 Hz, 1 H, C-CH-C), 7.68
13C NMR (75 MHz, CDCl3):  = 148.5 (Carom), 142.1 (Carom), 138.9 (Carom),
138.3 (Carom), 133.8 (Carom), 132.8 (Carom), 131.8 (Carom), 131.0 (Carom),
130.6 (Carom), 130.5 (Carom), 129.7 (Carom), 125.4 (Carom), 123.5 (Carom),
(dd, 3J = 8.1 Hz, 4J = 1.4 Hz, 2 H, CH-CF-CH), 7.49 [dd, 3J = 8.1 Hz, 4J = 1.4
Hz, 4 H, Te-C-(CH-CH)2-CH], 7.31–7.14 [m, 6 H, Te-C-(CH-CH)2-CH],
3
3
4.63 (t, J = 7.8 Hz, 4 H, N-CH2-CH2), 4.23 (s, 6 H, N-CH3), 1.87 (q, J =
8.0 Hz, 4 H, N-CH2-CH2), 1.37–1.18 (m, 20 H, Haliph), 0.86 (m, 3J = 7.0
Hz, 6 H, CH2-CH3).
1
121.84 (q, JC-F = 319.6 Hz, F3C-SO3), 115.2 (Carom), 112.7 (Carom), 55.6
(Caliph), 54.6 (Caliph), 39.4 (Caliph), 39.1 (Caliph), 31.8 (Caliph), 29.4 (Caliph),
29.3 (Caliph), 29.0 (Caliph), 28.9 (Caliph), 26.4 (Caliph), 26.3 (Caliph), 22.7
(Caliph), 14.2 (Caliph).
19F NMR (235 MHz, CDCl3):  = –78.5 (s, CF3SO3).
13C NMR (75 MHz, CDCl3):  = 162.3 (d, 1JC-F = 252.4 Hz, Carom-F), 147.5
(d, 4J = 2.4 Hz, CH-C-CHarom-C-CH), 137.7 (Carom), 130.6 (Carom), 129.6
3
(Carom), 129.3 (Carom), 126.9 (d, JC-F = 9.4 Hz, -C-Ctriazole), 121.69 (d,
MS (ESI): m/z (+) calcd for [M – OTf]+: 821.16; found: 820.92; m/z (–)
2JC-F = 23.8 Hz, CaromF-CaromH), 122.2 (q, 1JC-F = 321.9 Hz, F3C-SO3), 115.1
(Carom), 112.8 (Carom), 55.6 (Caliph), 33.2 (Caliph), 31.8 (Caliph), 29.3 (Caliph),
28.9 (Caliph), 28.8 (Caliph), 26.3 (Caliph), 22.6 (Caliph), 14.1 (Caliph).
calcd for [OTf]–: 149.06; found: 148.67.
19F NMR (235 MHz, CDCl3):  = –78.9 (s, 6 F, CF3SO3), –106.9 (s, 1 F,
Carom-F).
Funding Information
MS (ESI): m/z (+) calcd for [M – OTf]+: 1041.17; found: 1041.11; m/z
(+) calcd for [M – C6H5]+: 1112.12; found: 1112.71; m/z (–) calcd
[OTf]–: 149.06; found 148.66.
The authors thank the European Research Council (ERC) under the
European Union’s Horizon 2020 research and innovation programme
(638337) for financial support. Funded by the Deutsche Forschungs-
gemeinschaft (DFG, German Research Foundation) under Germany’s
4,4′-(1,3-Phenylene)bis[3-methyl-1-octyl-5-(phenyltellanyl)-1H-
Excellence Strategy – EXC 2033 – 390677874 – RESOLV.
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1,2,3-triazol-3-ium] Triflate (14OTf
)
Compound 14OTf was synthesized according to the general anion ex-
change procedure using Amberlyst® A26 (OH) (4.00 g), MeOH (40
mL), and compound 14BF4 (0.400 g, 0.382 mmol) dissolved in MeOH
(7.64 mL) to give 14OTf as a pale yellow sticky solid; yield: 0.295 g
(0.251 mmol, 66%). The spectroscopy data confirm the product
Supporting Information
Supporting information for this article is available online at
https://doi.org/10.1055/a-1372-6309. Su
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ortingInformationS
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ortingI
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14OTf 18a
.
References
4,4′-(1,3-Phenylene)bis[3-methyl-1-octyl-5-(phenylselanyl)-1H-
1,2,3-triazol-3-ium] Triflate (15OTf
)
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© 2021. Thieme. All rights reserved. Synthesis 2021, 53, A–H